#include #define ALL(a) (a).begin(),(a).end() #define RALL(a) (a).rbegin(), (a).rend() #define PB push_back #define MP make_pair #define SZ(a) int((a).size()) #define EACH(i,c) for(typeof((c).begin()) i=(c).begin(); i!=(c).end(); ++i) #define EXIST(s,e) ((s).find(e)!=(s).end()) #define SORTASC(c) sort((c).begin(),(c).end()) #define SORTDESC(c,t) sort((c).begin(),(c).end(), std::greater()); #define FOR(i,a,b) for(int i=(a);i<(b);++i) #define REP(i,n) FOR(i,0,n) #define dump(x) cerr << #x << " = " << (x) << endl; #define debug(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << endl; const double PI = acos(-1.0); using ll = long long; using namespace std; int main() { double a, b, x, y; double ans; cin >> a >> b >> x >> y; if (x*(b/a) < y) { ans = x*(a+b)/a; } else { ans = y*(a+b)/b; } cout << setprecision(20) << ans << endl; return 0; }